Many different types of machines are known to the art for cleaning containers such as trailers. The need for such machines is best illustrated by reference to trailers used for hauling meat. Such trailers generally become contaminated with pieces of meat, fat and blood during the hauling of the product. While it has long been the practice to clean such trailers, proposed governmental regulations will require more frequent cleaning. Furthermore, such regulations will require a very high cleaning efficiency, all of which dictates the need for improved cleaning processes and machinery.
Other types of containers also need to be cleaned regularly. Typical examples of such other containers include refrigerated trailers used for hauling produce or other food materials, cargo containers such as the type used on ships, railroad boxcars and the like. It is expected that mandatory cleaning regulations may be issued in the near future which will establish guidelines on the frequency and efficiency of the cleaning procedures used for these types of containers.
Until very recently, most cleaning of trailers and other similar types of containers was accomplished manually. A workman swept the trailer floor and cleaned the walls and ceilings using a high-pressure steam wand. This procedure is very time consuming and labor intensive and the effectiveness of the cleaning is totally dependent on the skill of the workman and the time devoted to each cleaning job. Moreover, this process is potentially dangerous since the workman or other people working in the vicinity could be injured by the high pressure and high temperature steam.
Two types of mechanical systems have recently been developed to make the cleaning of trailers faster, more economical and more efficient. A first type of automatic cleaner is the "boom" cleaner such as that described in the Crandall et al U.S. Pat. No. 3,961,983 issued June 8, 1976 for "Apparatus and Methods for Washing Interiors of Truck and Trailer Bodies." In this type of cleaner a washer head is mounted on the end of an elongate boom. The boom can either be stationary or movable along its axis. If the boom is stationary, a trailer is backed over the washing head, and water or a cleaning solution is sprayed from the nozzles as the head approaches the front end of the trailer. When the head reaches the front of the trailer, a rinse solution is sprayed from different nozzles and the trailer is driven slowly forward to finish the cleaning. Because the cleaning process in such systems requires both a driver for the truck and an operator for the cleaner, newer boom systems include an extendable boom. The trailer is parked, and the cleaning is accomplished by moving the boom back and forth into and out of the trailer. The water supply system for this type of cleaner typically includes separate nozzles for the wash and rinse solutions and separate supply hoses for the two fluids.
Several other patents can be mentioned to illustrate the other type of mechanical trailer washer. U.S. Pat. No. 3,534,746 was issued Oct. 20, 1970 to Posner for a "Portable Cleaner For Trailer Interiors." Posner's device includes a portable, self-propelled cleaner which comprises a rectangular frame and a plurality of nozzles disposed about the frame. The frame is mounted on a wheeled carriage which is powered by a motor for being driven into and out of the trailer body. A hose reel is mounted on the carriage for supplying steam or cleaning solution to the nozzles. Cleaning is accomplished by positioning the carriage at the rear of the trailer and driving the carriage into the trailer. Hose is unwound onto the floor of the trailer as the cleaning frame enters the body. The hose is rewound onto its reel by a system connected to the carriage drive motor. The Posner device does not include any type of system for varying the flow of liquid to the spray nozzles or for providing rinse and cleaning solutions to the same nozzles at different flow rates.
Another type of cart-mounted cleaner is described in Hartunian's U.S. Pat. No. 3,830,430 issued Aug. 20, 1974 for "Cleaning Vehicle." The spray mechanism of Hartunian is mounted to a power-driven frame and includes a plurality of nozzles adapted to be rotatively movable with respect to the base frame in at least two planes of motion. A tank of cleaning fluid and a high-pressure hose are mounted on the carriage. The hose and tank are interconnected to supply water to the nozzles. The patent does not include any mechanism for varying the water pressure or for alternately supplying wash and rinse solutions to the nozzles at different volume flow rates.
Yet another carriage-mounted cleaner is disclosed in McMahan's U.S. Pat. No. 3,973,988 issued Aug. 10, 1976 for "Trailer Washing Apparatus." This patent describes a different approach to trailer cleaning in that the power-driven carriage is movable into and out of the trailer while the hose reel, and wash and rinse tanks are located on a dock. The carriage includes rotating nozzles and valve means for selectively coupling the nozzles to either the wash or rinse tank depending on the operating cycle. The McMahan patent additionally provides for recirculation of liquids. For example, the wash and/or the rinse water may be recirculated to the wash tank. The rinse tank is refilled with clean water so that the final rinse cycle will always clean the trailer as thoroughly as possible. McMahan's patent also discloses various dock arrangements for providing the desired rearward slope for the trailer body and drain, filter and recirculation systems for carrying out the objects of that invention.
An improved carriage-mounted trailer washer is disclosed in co-pending, commonly assigned, patent application Ser. No. 785,196 filed on Apr. 6, 1977 by Richard McMahan for "Trailer Washing Apparatus." This application is a continuation of Ser. No. 696,647 filed June 16, 1976 and now abandoned. The McMahan application includes the recirculation, nozzle, hose and carriage systems of the earlier McMahan patent and additionally includes a time-delay and hose flushing system. The system stops the carriage when it reaches the front of the trailer body and starts the flow of clean water through the hose. Time-delay means delay the return trip of the carriage until the hose has been thoroughly flushed with the clean rinse water. In this manner the front of the trailer is rinsed with clean water.
Two other important features are also disclosed in the McMahan application. First, numerous dock arrangements are disclosed for permitting the carriage-mounted cleaner to be used in a variety of trailer cleaning environments. For example, various disclosed embodiments relate to cleaning alternate trailers backed up to a dock supporting the carriage, the carriage being pivotable about an angle of 180.degree. to be located selectively at the rear of either trailer. Alternately, an arrangement is disclosed for permitting cleaning of trailers driven alongside of a dock. In this arrangement, the carriage is mounted on a 90.degree. pivotable platform which is swung out and behind the parked trailer. The washer then enters the trailer for its cleaning cycles. A third embodiment permits the washer to clean a plurality of trailers backed up to the same side of a dock. The washer, in this embodiment, is mounted on a platform which is in turn mounted to a pair of rails and power means are provided for driving the platform along the rails to properly position the washer behind the particular trailer to be cleaned.
The second feature disclosed in the McMahan application is the recognition that different water volumes should be used for the various cleaning cycles. It is disclosed that the water flow rates ranging from about 50 to about 200 gallons per minute may be used. These water flow rates are substantially larger than those employed in the other prior art machines mentioned above and provide the McMahan apparatus with important cleaning advantages. A typical process using the McMahan system would employ a volume of about 200 gallons per minute for the washing step and only about 100 gallons per minute for the rinse. Since the speed of the carriage and the rotational speed of McMahan's nozzles remain constant, the extraordinarily high water volume causes a blasting effect on the interior surface of the trailer resulting in very efficient cleaning.
While the high water volumes used in McMahan may appear to be a radical departure from the other prior art systems, the departure does not result in a significantly more costly cleaning process because of McMahan's recirculation capability. New water is added to the system only for the rinse cycle, so additional water costs are minimal. Moreover, the efficient heating system for both wash and rinse solutions requires only minimal additional heat input. Most importantly, however, it now appears that the high water volumes and resultant increased pressure may be necessary to achieve the thoroughness of cleaning required by proposed regulations.
While McMahan's system does represent a significant improvement over the other types of carriage-mounted cleaning systems, it still has several disadvantages. First, the valve systems for providing different water volumes to the nozzles were not completely satisfactory. Precise control was difficult to achieve. Second, the hose arrangement of McMahan, with the hose reel on the dock, subjected the hose to unnecessary wear as the carriage dragged the hose into the trailer body. Also, the types of hoses required for delivering up to about 200 gallons of water per minute under high pressure are quite bulky and the hose had a tendency to pile up and foul the hose reel during winding. Third, the McMahan device did not satisfactorily flush the debris from the floor of the trailer, even if the trailer was sloped downwardly toward the carriage dock.
An improved trailer cleaning apparatus which overcomes the above-noted disadvantages of the prior art would represent a significant advance in this technology.